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- Author or Editor: H. Aly x
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Abstract
Tributyl phosphate was used in reprocessing of spent nuclear fuel inthe Purex process. The amount of uranium retained in the organic phase dependson the type of TBP/diluent. Destruction of spent TBP is of high interest inwaste management. The use of the oxidative degradation of TBP diluted withkerosene, carbon tetrachloride, benzene and toluene using potassium permanganateas oxidant was carried out to produce stable inorganic dry particle residuewhich is then immobilized in different matrices. The different factors affectingthe destruction of spent waste were investigated. The uptake and decontaminationfactor for both 152, 154Eu and 181Hf and the analysisof the final product have been studied.
Abstract
Synthesis and characterization of N,N,N',N'-tetrabutylsuccinamide (TBSA)was carried out and used for the extraction of U(VI) and Th(IV) from nitricacid solutions. Toluene was found to be the most suitable diluent for TBSAcompared with the other diluents tested. Extraction distribution ratios (D)of U(VI) and Th(IV) have been studied as a function of aqueous HNO 3 concentrations,NO3 – ion concentration, TBSA concentration and temperature.The results obtained indicated that U(VI) and Th(IV) are mainly extractedas UO2 (NO3 ) 2 . 2TBSA and Th(NO3 ) 4 . TBSA, respectively, and the IR spectra of the extractedspecies have been investigated. The values of thermodynamic functions havebeen calculated. Back-extraction of U(VI) and Th(IV) from organic phases wasalso studied.
Abstract
The concept of using paper chromatography on papers impregnated with liquid anion or cation exchangers is extended to the separation of trace elements through filtration on filter papers loaded with suitable extractant. The uptake of uranium, thorium and lanthanum from HCl and HNO3 media of different molarities by a filter paper treated with tri-octyl amine (TOA) is investigated. The effect of the different parameters on the uptake of the studied elements is experimented. A simple and fast radiochemical procedure is developed for the separation of La, Th and U from each other.
Abstract
The extraction of radio-mercury(II) by PTTDT was investigated as function of diluent, hydrochloric acid concentration, extractant concentration and certain foreign compounds in the aqueous phase. The extraction was found to be quantitative when chloroform was used as diluent and at low HCl or high PTTDT concentrations. Neither the presence of boric acid, nor several metal salts (NaF, CuSO4, ZnSO4 or Na2SO4) had any effect on the E%. The presence of chloride or bromide lowers the E% considerably. A radiochemical procedure was developed to pre-concentrate mercury from artifical sea water using an organic: aqueous phase ratio of 1∶100.
Abstract
The present overview presents a brief survey on the liquid-liquid extraction mechanism of metal chelates and adducts, the different reported reaction models and the most common methods used to follow the kinetics of extraction process are given. The effect of the different phenomena affecting the extraction rate and the importance of the kinetic information in connection with technical processes and counter-current modelling are also discussed.
Abstract
3-Formyl-4-hydroxy-N-methyl 2(H) quinoline (FHMQ) was synthesized and characterized. This compound was found not soluble in water or nitric acid solutions of different concentration. The uptake of Zr and Th from nitric acid by FHMQ has been investigated. The effect of shaking time on the percent uptake was studied. It was found that the equilibrium uptake of Zr is reached in one step after 2 hrs while in case of Th 4 hrs was required to reach equilibrium. The effect of nitric acid, metal ion and FHMQ on Zr uptake was studied. Studies on the retention capacity of 3-formyl-4-hydroxy-N-methyl 2(H) quinoline showed that its capacity decreases by increasing the nitric acid concentration for both Zr and Th. From the results obtained a selective method for separation of Zr from Th and U(VI) was developed using a floating bed column.
Thermodynamics of dinonylnaphthalene sulfonic acid (HD)
Extraction of trivalent americium, curium and californium
Abstract
The effect of temperature on the extraction of the trivalent actinides Am3+, Cm3+ and Cf3+ with the liquid cation exchanger dinonylnaphthalenesulphonic acid (HD) in toluene is studied. The different thermodynamic functions of this system are determined from the experimental results. It is found that the free energy variation for the extraction of these metal ions by HD is mainly determined by the entropic terms arising from the hydration-dehydration process of the exchanged ions.
Abstract
Synergic extraction of trivalent Eu, Gd and Am from aqueous perchlorate medium has been studied using mixtures of thenoyltrifluoroacetone (HTTA) and 15-crown-5 or 18-crown-6 (CE) in chloroform at (25±1) °C. Slope analysis of the extraction results indicated a general formula of M(TTA)3·(CE)2 for the extracted species. The stability order took the sequence Eu(TTA)3·(CE)2>Am(TTA)3)·(CE)2>>Gd(TTA)3·(CE)2 with 15C5 and Am(TTA)3·(CE)2>Eu(TTA)3·(CE)2>Gd(TTA)3·(CE)2 with 18C6. The synergic factors, extracton constants and formation constants of the extracted species were determined and discussed in terms of the correspondence between cavity size of the crown ethers and ionic crystal radii.
Abstract
Zirconyl tungstate ceramic-supported membranes were developed and characterized. The transport process of Cs(I), Sr(II) and La(III) from the anode compartment to the cathode was investigated. The cationic fluxes for Cs(I), Sr(II) and La(III) were found to be 9·10–10, 2.7·10–9 and 2.4·10–9 g·eq·cm–2·s–1, respectively. The transport numbers of these cations were found to be 0.12, 0.07 and 0.09, respectively. Separation of Cs(I), Sr(II) and La(III) was achieved using EDTA as a chelating agent in the anode compartment. Cs(I) was successfully separated with a decontamination factor of 97% from simulated intermediate level liquid waste (ILLW) containing Cs(I) and Sr(II).
Abstract
The extraction of the trivalent lanthanides Eu, Tm and Yb(Ln) by crown ethers (CE) 12-crown-4 (12C4) and 15-crown-5 (15C5) in chloroform from perchlorate aqueous media of constant ionic strength is investigated. The effect of [H+], [CE] and [ClO
4
–
] on the respective distribution ratio (D) is elucidated. Slope analysis of these results indicated that the extracted species are of the type Ln(OH)
2
+
·ClO
4
–
(CE)2. The extraction constants obtained are in the sequence 15C5>12C4 for the CE's and Eu
Tm<Yb for the elements investigated. Based on the separation factors elucidated, Tm(III) and Yb(III) are separated from Eu(III) with high radiochemical purity; >99.5% by three (or four) successive extraction and strippings.
